1. Field
This disclosure relates to an additive for an electrolyte of a lithium secondary battery, an organic electrolytic solution including the additive, and a lithium battery including the organic electrolytic solution.
2. Description of the Related Technology
Lithium batteries are used as driving power sources for portable electronic devices, including camcorders, mobile phones, and laptop computers. Lithium secondary batteries are rechargeable at high rates and have a high energy density per unit weight of about three times higher than that of conventional lead storage batteries, nickel-cadmium (Ni—Cd) batteries, nickel-hydrogen batteries, and nickel-zinc batteries.
Since lithium batteries operate at high operating voltages, they are not compatible with aqueous electrolytes highly reactive to lithium. Lithium batteries mostly use organic electrolytic solutions. An organic electrolytic solution may be prepared by dissolving a lithium salt in an organic solvent. An appropriate organic solvent for the organic electrolytic solution may be stable at high voltages, and have a high ionic conductivity, a high dielectric constant, and a low viscosity.
When a lithium battery uses a carbonate-based polar nonaqueous solvent, an irreversible side reaction between the electrolyte solution and a positive or negative electrode may occur during an initial charging process, causing excess consumption of charges.
As a result of the irreversible side reaction, a passivation layer such as a solid electrolyte interface (SEI) may be formed on a surface of the negative electrode. The SEI may prevent decomposition of the electrolyte solution during charging and discharging and may serve as an ion channel. The higher stability and smaller resistance the SEI has, the better lifetime characteristics the lithium battery may have.
The irreversible side reaction may also result in a protection layer on a surface of the positive electrode. The protection layer may prevent decomposition of the electrolyte solution during charging and discharging and may serve as an ion channel. The higher stability and smaller resistance the protection layer has, the better lifetime characteristics the lithium battery may have.
Therefore, there is a demand for an organic electrolytic solution able to form such a SEI and protection layer with improved stability and low resistance.